Power scaling

Disclosed are systems and methods for measuring and calculating parameters to control and monitor a power transfer in an implanted medical device, including operating the device in a plurality of scalable power modes and/or coupling modes. The system may shift between or among power and/or coupling modes based on input such as data received over system communication lines, programmable timers, or electrical loading information. The system may also shift between or among power and/or coupling modes based on calculated amounts of coupling, levels of detected heat flux, and/or amounts of estimated temperature changes.